Where are you seeing that?
That should probably happen, independent of whether sound is getting to the computer, so that only tells us that your mic and headphones work, but not much more.
Do you see the meter respond to your voice in the “Sound Preferences”?
Have you given Audacity permission to use the microphone? (See: No signal from USB turntable (Mojave) [SOLVED] - #6 by SonArc)