Macbook - Skype is not detecting Microphone

Please follow the instructions below : 

option 1:

Open System Preferences in the Dock 

Open Security & Privacy, then select the Privacy tab.

Click Microphone in the Sidebar then checks Skype to access your Microphone.

You might need to unlock the padlock and confirm the change.

If that does not work you may need to reinstall skype

Skype for Business

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Option :

If you can't see Skype for Business under Security & Privacy > Microphone,

We will need to copy the "TCC.db" file from a known working Mac, onto the one with the issue. 

To find this file please go to the below directory;

~/Library/Application\ Support/com.apple.TCC/TCC.db

(To find this open "Finder" > Press "Shift, Command & G" > type "~/Library/ - and navigate from there
Replace this file with the TCC.db file from a known working device
(Or grab the file from the DTS share in Problem Fixes > Macbook Skype Mic)

Hopes this will help you to fix the issues with the Microphone.