Hiring great programmers is hard. I have been advised that great programmers have great ideas. You can also ask questions (open ended) about coding during the interview.
Even telling the programmer to create a prototype to solve a certain problem helps a lot. You get to understand the programmer's approach in solving problems
We've put together several take-home mini projects as Github repos that have instructions and sample data or a starter template. Candidate clones the repo, commits frequently, and builds something demonstratable that works or doesn't. It's structured to be similar to the kind of early real task they would get. Key is it's open book, they can google and stackoverflow as much as they want. We can see evolution of thought process in the commits and have a good discussion in followup conversation. We do this after they have passed a phone screen or onsite interview and we are interested. So far, we like the results.