Hi Aspirant

If you are really interested to be an ethical hacker there is no prerequisites .You need not to know anything but you must be entusiast .

This field is mostly preferred by CS/IT students because they can make use of it.

Simply ethical hacker is someone who helps the govt./nation to reduce cyber crime and not to indulge in that kind of criminal activity .So it becomes quiet sensitive for anyone who wish to do it.

You can do it by joining some online courses or offline courses in your city.

Some online platforms are:

Internshala

Udemy

Coursera

Udacity

Edx.org

There are many more whichever you choose.

Hope this helps.

All the best.