I asked what YOU use, not what should I use.
I don’t take a phone, and the idea of measuring a run fills me with horror
I know this is the wrong thing to say, but…Have you thought about just going for a run without measuring it? Just run for sake of the fact that you can run, and it’s an amazingly freeing thing to do?
Road bikes are for hurting yourself and getting fit, running and MTB are just for shits an’ giggles.