What tool do you use to temp?

Not sure if this type of post is allowed so please remove if not- but wondering what tool you use to temp when charting?

I used to use a bbt thermometer I found on amazon, it worked really well but my sleep is no longer consistent and I can’t guarantee that I’ll get 3 hours at a time, let alone at the same time every day.

I’ve seen suggestions like tempdrop and Apple Watches, wondering what everyone uses aside from bbt? Thank you!!