How to enable remote microphone on remote desktop

Solution 1:

Before connecting to the remote computer, click on Show Options > Go to Local Resources tab > click Settings in the audio configuration. You can enable the recording from your local PC to the remote computer.

Solution 2:

On desktop Windows clients, the mic setting is in the "new connection" dialog, under Local Resources / Remote audio [Settings...] / Remote audio recording: Record from this computer.

However, it sounds like you're trying to record audio on the remote computer, which is not an available option for the native clients. It's possible that other clients can support this feature, but it may also be a limitation of RDP, which would make it impossible.