Orange Dot Microphone just appeared ....

No one is listening to your phone conversation (other than the person you have called, or called you). As a microphone is required for every phone call, the orange light will appear when making or receiving a phone call.

If you see orange or green indicators in the status bar 

With iOS 14, you might see an orange or green indicator in the status bar on your iPhone. These indicators appear when the microphone and/or camera are being used by an app.

• An orange indicator  means the microphone is being used by an app on your iPhone.

• A green indicator  means either the camera or the camera and the microphone are being used by an app on your iPhone.

The “new feature” is simply a dot that indicates that something that has always been happening, is happening!

It was activated after a recent update.

Open the Control Center to see which app is doing it.

Have you made or received a phone call on the device?

For every one of those phone calls, your microphone has been used, thus the orange dot will appear. The appearance of the orange dot is a simple security measure included in the last iOS update.