BookBeat has its own app for Apple Watch. You can read more in our article about using BookBeat on the Apple Watch.
Other smartwatches
We don't have an app for Wear OS or other smartwatches. On many smartwatches, you can still use the watch's own media controls to pause, play or skip in a book. The book is always played from the BookBeat app on your phone, though, so you need to have your phone with you.