While many desktop PC systems might not have a built-in webcam and microphone way more do than people realize. Even if you never use Skype or a voice system like Cortana, that doesn't mean that your system doesn't necessarily have a microphone and camera! And of course just about 100% of laptop systems and tablets have both a camera and microphone, whether you use it or not.
Sure you can put a piece of tape over the camera ” not a bad idea on a PC, though I prefer something that slides to offer access as needed (like this unit) ” but that doesn't stop the microphone being utilized. Fortunately Microsoft has been putting huge efforts into locking down peripherals from unauthorized programs and most users will find that if their anti-virus gives them a clean bill of health, they should be free of sneaky malware accessing cameras or microphones.
But there are also programs in the Windows world that legitimately need access to one or both, and that's where a quick visit to your Settings and Preferences is smart. To start, though, just go into Win10 search (aka Cortana) and type microphone:image: https://www.askdavetaylor.com/wp-content/uploads/2018/07/win10-privacy-access-microphone-1.png
It's not the default match you want to choose, however, but the one below it that says Microphone privacy settings. Click or tap on that to proceed.
You can see that you can en masse turn off all access to the microphone for any and all programs on your Windows computer at the top, which is redundantly managed by the On/Off Allow apps to access your microphone. Assuming it's enabled, you'll want to scroll down a bit to see what apps and programs have requested access to your microphone and which have been granted that permission.
As you can see, I have more disabled than enabled. Why does Feedback Hub and HP Smart need access to my microphone? (oops! Need to disable Feedback Hub, now that I'm looking at it a bit more closely).
Microsoft Edge is a special case too: Notice that you can enable the Web browser gaining access to the microphone but you'll still be able to grant or deny access on a per-site basis as you explore the Web.
But what happens if you accidentally disable access for a program that you really do want to have access to the microphone? Let's find out! I'm going to disable Skype from both camera (a similar process to the above) and the microphone (as shown above). Now when I launch Skype, I'll simply get prompted to allow access:
Not too much of a crisis, really. So my counsel would be to always shut down everything you're not entirely sure you want to grant access to your camera / microphone / etc and then know that any decent program will always be able to prompt you and re-enable as needed. Now, be careful out there!