You can track your steps using the Health app on your iPhone. If you want to log your steps properly and carrying your phone is not an option, please sync your Apple Watch with the Health app. Here's how you can do it:
- open the Health app
- go to your profile, then tap Devices
- select your Apple Watch
- hit Privacy Settings and make sure that Fitness Tracking is turned on.
Once it is done, you can track steps using your Apple Watch.