Use Siri on your Apple Watch - Apple Support
support.apple.com › en-us › HT205184Jul 02, 2020 · On your Apple Watch, see if Hey Siri is turned on. Tap Settings > Siri. Restart your Apple Watch. On your iPhone, go to Settings > Siri & Search and turn off Listen for "Hey Siri." Then turn it on again. See if the microphone or speaker on your Apple Watch is blocked. For example, if your device has a protective case, remove it.