Can someone hear me through my apple watch if I’m not on the walkie-talkie app ?

As in eavesdropping? That is not a function Apple would intentionally allow.

You can bee heard if you are on a phone call.

You can be heard if you are on a FaceTime audio call.

You can enable the “Noise” app to monitor sound levels for sounds that are too loud.

Siri can here you when you say “Hey Siri”, which may be processed by Apple servers.

You could install a 3rd party app that works with the microphone.

Apart from the normal and expected use of the microphone for which BobHarris provides an excellent list, there is very little probability your Apple Watch could snoop on audio activity. Any such eavesdropping or spying would need two conditions, both of which would be very unlikely;

* Your Apple Watch would need to be infiltrated by the spyware, which could only be routed as a software update through your iPhone. This is starting to sound like hard work for the bad guys....

• Your Apple Watch would have to send any monitored audio back via your iPhone, so the iPhone's software would also have to be subverted

In reality you would almost certainly notice any spy activity, because there would be a significant increase in communication activity to pass the snooped audio back to the bad guys. This would increase battery drain, and you would be here complaining about poor battery life.

it depends on how you think its happening. apple can answer that question