Hacked account

Hello,
Recently I found out that my Minecraft account was hacked. A Russian guy changed my name from Othalar to ragup1ay. I checked my email on the site "have I been pwned", it turns out there were a couple of major leaks. Now I changed my password. He uses the email "ra**il@mail.ru". I checked the internet and I found out that he also uses steam with 2 different names: ragup1ay and kaosgaming71. I wanted to report this to Mojang but I don't know how to do that. Can anyone tell me what to do about this?
Thanks!