Do you measure NPS/CSAT in your app/product and how?

Hey fellow Indiehackers 🤗
we have a small SaaS product and looking to learn more about our users, what we can do to improve their experience and why they (eventually) churn.

What's your experience measuring NPS or CSAT (including additional feedback questions) inside your app and what service or tool do you use for that?

Thanks a lot for your insights!