Apple said in a statement on Monday evening that it had identified a solution to the problem and will release it in a software update later this week. Mojave that have a recently added FaceTime feature.
It is activated when you call someone via FaceTime, drag up to add another person to the call, and add your own phone number. Then the person who initiates the conversation can hear the live sound of the other person's phone even though the recipient has not accepted the conversation. Their screen does not indicate that their conversation is transmitted. In some cases, the bug can display a live video from the other person by pressing a volume button to reject the call. he could even see the video of the people he was calling.
To avoid becoming an error, disable FaceTime on all your devices until Apple software updates are released.
On iPhone or iPad go to Settings -> FaceTime and turn off the green button at the top of the screen. To turn it off on Mac, open the FaceTime app and go to FaceTime at the top of the screen, then select "Turn FaceTime Off".