First of all, don't worry: the mouse is just as frightened of you as you are of him. A wild (non-pet) mouse in your house will have NO desire to approach you whatsoever. And yes, they can climb, but it doesn't matter because they have no interest in climbing up into your bunk bed, they come out late at night looking for food. They deliberately stay low for easy access to escape if needed, so they won't be climbing around up high in your room, they will stay low, near the edges of a room and sniff for food. So unless you have an open bag of potato chips in your bed while you sleep, you don't need to worry.
My best tip (aside from not worrying about him trying to get in your bed) is: Don't keep food in your room, and be sure to clean your room of any food crumbs and wrappers after you do eat in there. They will most likely avoid your room all together if you don't have any food. Remember, they can smell the tiniest crumb, so try to avoid eating in your room.
Ignore the person who said it's probably nesting in the paper. You were right in what you said, he was simply hiding in the paper. His nest will be somewhere hidden, most likely in a basement or attic, possibly behind a wall that has a small access point. But he's not going to build a nest behind your dresser.
I do agree with the person who suggested a live trap to catch him, but I wouldn't leave the trap in your room, since you will have to bait the live trap with food, like peanut butter. Put the trap in the basement or kitchen up against a wall. "Have-A-Heart" is a good live trap brand. Then you or a parent can release him in the woods. Or, you could try and convince your mother to hire an exterminator if you continue to see him.
Just keep food & crumbs & wrappers out of your room, and don't worry. They truly want nothing to do with you. He was probably just as panicked as you and just wanted to hide. I am the Manager of a Pest Control company (exterminator), and in all the years I've heard some crazy stories, but I have NEVER once heard of a mouse or a rat going after a person or trying to bother them or get in their beds.
So relax, and good luck!