How to find a Bluetooth Mouse
Solution 1:
Unfortunately, the Magic Mouse has no such functionality.
If you have a cat, check its bed.
If you have a couch, check between and behind the cushions.
If you have a messy computer desk, (like mine,) give it a clean.
Could somebody have hidden it to play a prank on you? Check coat pockets, cookie jars, inside shoes, on top of bookcases....
It'll be in the place you least suspect it to be, and when you find it you'll remember that's right where you put it.
I once 'lost' an iPad Mini. It was with a stack of other iPad Minis in a horizontal file cabinet drawer, but it had cunningly secreted itself in a mostly invisible slot in the front of the drawer itself.