I hate to sound unsympathetic, but those things may not be the best move to take on any vacation, much less a Disney trip.
With any hotel, there is a chance things may go missing. I believe there is a house safe at most hotels if you really need it. Otherwise, stuff should be kept in a suitcase out of sight. Most thieves, if they are Disney-employed or not, will not choose to go through a suitcase but go for whatever is being left out.
If they choose to go through your stuff, there really isn't much you can do but keep valuables with you and not bring really caluable or uninsured stuff with you on your trip.
Also, there is not much Disney CAN do. Most hotels do not take responsibility for personal items left in rooms, and I can't imagine the Disney resorts are any different. I am sure they take theft seriously, but other than using thousnads of security cameras everywhere on property, it is hard to prove anything.