Making a scary game but how do I make the arms move in first person up and down?

so heres my game, i tried some scripts on the internet and i coulden't find anything so can someone please explain some of this stuff. Heres the game actually https://web.roblox.com/games/4968984824/The-Chaser?refPageId=5d7c019b-f529-4d50-a1ff-90c50624bb20