She spies on him, secretly listens to their phone conversations on a party line.

You see, I listened secretly from the next room when they met.

Is it polite that such a person listen secretly?

I think it wasn't cool for guys to like them after that, but I probably secretly still listened to them.

She had to secretly listen to pop music because her parents were against it.

She stumbles upon a hidden room that allows her to secretly listen in on Parliament's session.

We used to secretly listen to Ferencváros matches on the radio".

That means no one can secretly listen to tag/base station conversations.

They all listen secretly to other people's cellular telephone calls.

With friends she secretly listened to forbidden radio stations from the west.