I don't think there's such a plugin existing atm.
I'm not even sure there's any library or support in browser to allow you to detect and use the microphone as an input source (produce a sound in the microphone to trigger an action in game) at the moment.
You may want to try and use Construct2's SDK
to make one.
Please don't bump/be impatient
If you have more informations to add, use the "Edit post" option in "Post options" on the last post you made.
Bumping is tolerated every 24 hours, not every 24 minutes.