You want to ask open ended questions - ones where you have divergent thinking displayed. One I read in a book was "what would you do with a brick?"...if they answer only one or two things, well, that's not as creative as the guy who can come up with 20 use cases, right?
A lot of interview questions revolve around convergent thinking, where there is only one right answer...those are important, but creativity is equally and sometimes more important.
The brick example you should change based on the needs of your request to the person you're asking...eg, how many colors can you name, etc.
Ask them to tell u a story in detail, any kind of story and go from thr
If they could tell you a joke you have never heard, that he is the one.
what inspires them?