change an image on hover?

hey, could anyone provide code for, like.. something that makes an image on your profile switch to another image when a mouse hovers over it? i want to put a picture in the corner of my profile that switches and jumps when a mouse hovers over it.

also, i wanna know the code to make it expand a little bit on top of this. i think i already know it but i'm not sure how to combine the two. making it hop a little upon hover would also be really cute

thanks for the help!