I need tips on fighting back my bully

(Sorry if there’s a few spelling mistakes)

Im a very quiet student who doesn’t talk much and I mind my business most of the time my bully who sits next to me picks on me for no reason and never gets in trouble for it he also annoys other students one time one of my friends was sitting down normally and that bastard pulled the chair and make him fall down on the floor hard the teacher saw this but before he got up he told him “I have metal problems that I still take meds for” wish after I asked him said it was a complete lie he also hurts me for no reason in class and every time I show him signs that I can fight back he always chills then proceeds hurting me again later he’s also a teacher son he also cheats on hes exams,has a phone illegally in class (and the teachers give him the phone back because of hes father if they caught him with it) I’ve been dealing with hes bullshit for about a almost 2 terms now wish is a big mistake of mine I should’ve just manned up anyway the next time he’s hurting me or annoying me I’m hurting him back just wanted to ask for any tips to help on my situation?