My 3 year old Yorkie and his ball?

Ok. My little boy has had problems with balls for a long time. That being so, after first seeing how he behaved possessive with it I avoided getting him balls that could fit in his mouth. But recently I took him to my local dog park in Brooklyn heights and he picked up some dogs tennis ball, I tried to take it from him but he held on so tight that it was impossible without breaking his teeth. So he took it home and when he went for water and food he rested the ball down near the bowls, when I reach for it he grabbed it and ran under my bed and since then he's only been coming out to eat and drink water shortly, never being more than a few inches from the ball. I don't want to have to chase him out of there with a broom; I've tried meat, I've tried new toys and treats but he's not budging. Any ideas for getting him out? I'm afraid I might have to get my bf to lift the mattresses and let me get him out :( maybe I'm more wondering...does anyone else have this problem with their dog? I love him dearly so ppl please no rudeor smartass remarks. Thanks :)