I agree with mangoandmimi. You can put just about anything up to a hamster and they will probably climb in, this dosen’t mean they “love” it.
People use hamster balls as an exercise for them. Your hamster will get very stressed from this. They have no way to get out if they are feeling stressed and no where to get away from the hamster ball. The hamster ball also provides poor ventilation. If there are big wholes in the hamster ball, a ham could get their foot or toe(s) stuck in it and even get pulled out. This would obviously be painful, stressful, and scary.
Stress weakens the immune system. When the immune system is weakened, bacteria, diseases, etc. are very hard to fight making the hamster prone to bacteria etc.
If you want your ham to have exercise, there are better, safer, and much less stressful options. You can free roam (Only Syrians, I don’t reccomed this with dwarfs and Chinese’s because of their size but this is your chose), put the, in a playpen, or use the bathtub method (if you don’t know what these are I can answer it for you). I apologize for my awful writing skills as it is really late and I’m super tired lol.