I usually don't write about hardware because it doesn't fall under the banner of "free." However, I've been asked about this topic a lot this year so I thought I'd cover it.
The last nine months have put most of us in front of a webcam more than ever before. Which is why I've had more questions about webcams and microphones in this year than in the previous twelve years combined. One of the things that I've been telling people when they ask about webcams is to first make sure you have good lighting around you. Good lighting can make you look good on even an average webcam. Likewise, a good microphone can make a world a difference in the quality of your online meeting hosting experience and your students' viewing experience.
The lighting set-up that I use in my home office consists of three inexpensive gardening lights positioned over head and one small ring light positioned in front of me just above my webcam. The ring that I've been using is fine, but lately I've noticed that it's not quite as bright as it was when I got it a few years ago. Therefore, I jumped on a "Black Friday" deal and ordered this 10" ring light with a tripod from Amazon.
The microphones that I've used and recommended for years are Blue Snowball microphones. I own two of them and have lugged them all around the globe to use in workshops. Unfortunately, they've become so popular that they are hardly ever in stock these days. My school tried to buy some at the start of the year and couldn't. Instead, we ended up getting these Fifine microphones and they've been fine but I still like my Blue Snowball better. Either one is a great improvement over using the built-in microphone on a laptop. Speaking of built-in microphones, when you show videos in Zoom be sure to change the sound input settings to pick up the computer sounds instead of just the microphone sounds.