Reboot your Mac, then re-assign the permission to see if there is any difference. The meter works just fine showing sound being made into the built in mic when that's selected, but not for the line in option. First of all, please go to System Preferences > Security and Privacy > under the Privacy tab > Microphone and un-assign Teams the permission. If the headset is plugged in it will use it, if not it will use the internal mic on the MBP. If I go to the Sound preferences section, and select "Line In", it shows no input on the meter there, no matter how much sound I'm making with the microphone. Plug that type of headset into the headphone jack on the MBP and then set the input to built-in mic. However, since that first time, the audio line in port has not worked correctly. If you are plagued by the voice chat issues on Fortnite on Windows 10, 8, 7, or even Mac, you need to check this mic problem and try methods to solve it to enjoy the game as before, especially when the Fortnite speaker is not working, neither. After I was finished, I switched the default back to the internal mic.
So I got out my microphone that I routinely used on my PC, plugged it into the line in port, changed the appropriate settings, and it was good. Go here for step-by-step instructions for checking your Windows drivers. You could try a dynamic mic which does not need a supply but audio outputs from dynamic mics is very low and will probably not work. When your microphone isn't working in Windows 10, it might be a problem with your drivers. This can be arranged externally if you know how.
#BUILT IN MIC NOT WORKING MAC MAC#
I got a new MacBook a few weeks ago, and quickly found the internal microphone to be lackluster for my musical needs (I often record myself singing, as part of my voice training). PC's that have a mic input have a supply voltage to feed the transistor but the Mac does not have a mic input, only a line in which means there is no supply voltage.