Google Meet 

Follow these steps: 1) join your next Google Meet early; 2) Click on the vertical ellipsis in the lower right corner; 3) select "Settings"; 4) within the audio tab find microphone; 5) click the drop-down arrow/chevron next to whatever microphone is selected; and 6) select the mic you intend - which may also be an "earbud" or in-line microphone headset that you have plugged into the side of your computer.  

Then, test your settings with another meeting participant to make sure they can hear you well.  If this doesn't work, you may need to reset permissions within your Chrome browser to ensure that your computer is allowing Chrome to utilize your microphone(s).