Please ensure that the microphone you are attempting to use isn't muted (please refer to the manual for your specific microphone to find out how to use the mute feature if equipped).
Be sure to follow this guide here before proceeding with the below steps:
Go to the Start menu and type in Privacy settings and press enter.
In the menu on the left of that window that has just opened, click on Microphone.
Make sure that the statement "Microphone acess for this device is on" is shown above the "Change" button, if this is not enabled then please click on "Change" to switch it on.
Scroll further down this list, and ensure that "Allow apps to access your microphone" is enabled and that the related application is enabled in the "Choose which Microsoft Store apps can access your microphone" section of this window.
Scroll down a little further and ensure that "Allow desktop apps to access your microphone" is enabled.
If the microphone still doesn't capture any audio, please arrange a remote session with one of our technicians for further diagnosis, there may be a driver or hardware related fault.