Hi , it has happened to my hams many times before I had hamster balls with a lid that locks in place. I don't know the name of the company, but they are see-through and the lid is always colourful.
Those are the only hamster-proof hamster balls and I love them! Funnily enough, by the time I found them and bought them - one of my Syrians is blind and so she just free-ranges around her cage ( as she doesn't like a ball for obvious reasons ) and my other ham is really elderly ( but...he used to really love his ball - and he never escaped from this one! Ever! Unlike from all the other ones!
x