How to turn off orange light near camera on iPhone screen?

Something is using the Microphone on your iPhone. Open the Control Center, by swiping down from the top right hand corner of your iPhone which will show what is using the microphone.

Open Control Center, and at the top, you'll see the icon for the camera or microphone and which app was using it most recently.

If Control Center displays “Unknown Device” next to the microphone or camera indicator, it may indicate that an accessory connected via Lightning, USB-C, or Bluetooth — such as an external microphone, webcam, or certain headsets — is requesting audio or video input, but iOS is unable to fully identify the device.

See the pics below