My Name is Paul one of the Community Expert and a Windows User like you. I am sorry that you are having issues with your MIC using ZOOM App. First lets try to perform some triage to replicate the issue.
1. Check Privacy Settings.
* Click Start and search for PRIVACY SETTINGS and open it.
* Look at the left side for APP PERMISSIONS and choose Microphone.
* Make sure that the access to your MIC is ENABLED.
* If you downloaded it from MS Store scroll down and make sure that ZOOM has access.
2. Check if the MIC is the Default Device
* Click START and search and open Sound Settings.
* In the Right corner you will going to see SOUND CONTROL PANEL. click it.
* Go to Recording TAB and make sure that your MIC is under default.