For Windows Vista, 7, and 8, normal operation may not be guaranteed because Microsoft has ended support for these operating systems. (Reference)

In the oCam main window, click the Sound button.

The following menu will appear, and by default, No Microphone Recording is selected.

Select the microphone you want to record. ( If your microphone does not appear in the list, refer to the instructions below. )

Once selected, the setting will be applied as shown below, and the microphone audio will be recorded together.

If the microphone device does not appear in the list above even though the microphone is connected, proceed as follows.

( If, as shown below, no microphone-related menu appears at all and only the system sound recording menu is shown, or if a microphone item appears but not all microphone devices are listed, or if you are using a separately purchased audio interface, the audio interface device rather than the default microphone device should appear in the list. If it does not, follow this procedure. )

Go to Start Menu - Control Panel.

In Control Panel, find and click Sound.

The following window will appear. Click the Recording tab.

In the Recording tab, right-click the white area where it says No audio devices are installed to open the pop-up menu. ( Or, if recording devices are listed but the device you want does not appear. )

Click Show Disabled Devices.

Select the microphone device you want to use, right-click it, and click Enable.

( If you are using an audio interface, a separate recording device called Line In may appear instead of a microphone, and you should record using that device. ) 

In oCam, click the Sound button to check whether the microphone device now appears correctly.