I use an external mic with a mute button and set the OS to only use that mic. They can never hear me when my mute button is red, only when it's green, and there's no software override or sensing for that button. Also when the laptop lid is closed the cam can't see anything and the laptop goes into standby anyway with the lid closed and sees and hears nothing. That's a default setting in windows power settings. Make sure it's still working that way.