When the Prophet (ﷺ) was affected by sihr, he found out who perpetrated the sihr, how it was done, and where it was placed. He (ﷺ) also made this information public. Therefore, this information can be obtained and made public if it is in the public's interest.
With this information, the victim can at least avoid the perpetrator rather than being completely aloof, unaware to how he is being harmed and by whom.
With this information, the victim can take the means to protect himself and his family immediately. This can be through acts such as refraining from eating their food, or washing their gifts with recited water.
Furthermore, knowing so allows the victim to gather evidences, and when required one can provide them to judges and the people of authority who can take these criminals into account.
When the Prophet (ﷺ) was affected by sihr, he made duas to Allah for help. Two angels descended and showed him exactly where the sihr is, who did it, and where it was placed as narrated in Al-Bukhari, Muslim & others.
It was narrated that 'Aishah said: A spell was put on the Prophet (ﷺ) until he imagined that he had done a thing (intimacy with his wives) when he had not actually done it. He would make dua, and then more dua, and one day he said, "Do you know that Allah has shown me in what lies my cure? Two men came to me and one of them sat at my head and the other at my feet. One of them said to the other, 'What is ailing the man?’ He said, 'He has been bewitched.' He said, 'Who has bewitched him?' He said, 'Labid ibn al-A'sam.' He said, 'With what?' He said, 'With a comb, the hair that is stuck to it, and the skin of pollen of a male date palm.' He said, 'Where is it?' He said, 'In the well of Dharwan.'"
The Prophet (ﷺ) went out to the well, then came back and said to 'Aishah, "Its date palms are like the heads of devils." I said, "Did you take it out?" He said: "No. Allah has healed me, and I feared that might bring evil upon the people." Then the well was filled with earth. [Al-Bukhari & Muslim]
Couple of benefits to note from this report:
The victim is able to uncover who did the sihr, why & how.
One way to obtain this information is through dua & salah.
This information may be provided in a dream.
The best & easiest way of finding out who committed the sihr & evil eye is to do exactly what Prophet (ﷺ) did—Dua:
Wake up for tahajjud, repent from all sins, and pray. In each of the positions of dua, beg Allah to show you the people who perpetrated the sihr; when they did it, why, how and where it is located.
Keep praying and begging, for days and weeks, until you begin to see the people in your dreams. Do not take it as evidence until you see them at least a couple of times. The more you see them the more likely they are the perpetrators.
You may see every detail: exactly who did it, exactly how they did it, exactly where they placed it and so on. Thereafter, make dua to Allah to grant you the ability to destroy the sihr in the dreams by reciting Ayatul-Kursi, or any verses & words exalting Allah.
If possible, go and investigate those areas you saw in the dreams, destroying any sihr you find by burning it and saying Bismillah wa Allahu Akbar, or any other verses/words exalting Allah. If you cannot see or find anything at those places then simply spray that area with recited water.
One may also close their eyes and imagine those places & keep blowing upon them by saying Bismillah wa Allahu Akbar intending to burn the sihr.
As for the evil eye, blow upon the person who you saw in the dream intending to burn the evil eye.
May Allah Ash-Shafi cure all whom are suffering from sihr and evil eye. Allahumma Ameen!
All praise is for Allah, Rabb of all that exists.