How to deal with ual harment?

I am not even in high school yet but I think I'm being hared. This guy has been bothering me all year but it is getting worse. He constantly asks me questions like "will you go out with me?", "will you kiss my sc?", and "will you hug me?". He purposely rubs his body against mine when walking by and when we are next to each other sitting or standing he gets really close. He sometimes comes up from behind me and attempts to hug me which is uncomfortable because I'm a girl and I don't appreciate being treated like a slut. I've always had a lot of self respect and I would never let myself be taken advantage of. He even stoops to the level of stealing my name tag on my locker or putting his name tag next to mine or above it. e stay in homeroom all day and have all our cles by the same teacher so there is no getting away from him. I have tried ignoring him, tried confronting him calmly, tried yelling at him, and even tried to tell other people but nobody seems worried.