I had a creepy teacher except he used to harass me and stop me in the corridor at break time to complain about my work. I left his class when he actually threatened me for not doing well in an essay. He acted like it was just frustration on his part but it was inappropriate comments and obsessive behaviour.
As the others said, keep a friend with you if he asks you to do anything you are not comfortable doing. If you trust your school to respond appropriately, inform the head or a teacher you trust. Failing that, tell your parents and ask if they can take it up with the school. Teachers should hopefully take a complaint from them very seriously.