How to implement idea without it being stolen

I have identified a problem that if solved could be worth a lot of money.

The problem is that I have 0 know-how in the manufacturing of said idea and it’s actually impossible for me to test my idea because of that hurdle.

I’d like to take my idea to someone who is an expert in the field I’m talking about who could help me manufacture my product.

I have an expert in mind who is proximally close to me, but I don’t want to take the idea to them, have it work, and them just cut me out and run with it.

How do I protect myself and move forward?