There are a few avenues here for you. When you say stolen the design - what do you mean? Did he/she steal images or drawings?
Is the product patented? You could file an entitlement dispute over the invention.
Generally for IP infringements you can claim either damages or an account of profits.
You need to obtain an advice from an IP lawyer to determine your position fully but you will need to give the lawyer more information so they can determine the best course of action.