Ferrets dig. They dig into rabbit burrows and similar to hunt for their prey. Often they may even take over the warrens or burrows of those that they prey upon.

Domestic ferrets also dig. They dig in their food dish and spread it all over making a mess. They never put it back into the dish either. Hmph.

So here's a simple thing you can do for a ferret. Take a large plastic tub with lid- something a bit larger than a shoebox is ideal. Fill it 3/4 full with lima beans or similar. They are cheap and work great for this. Cut a hole in the top of the tub about 3" or so in diameter. The ferret will be able to get into this, trust me. They will climb in and dig, dig, dig. The amount of beans getting out will be none to minimal. It lets them get the digging habit out of their system and their food still in the dish (yeah, right).

If the bean box can fit inside their cage, all the better. :)