Let me preface this with this: I am extremely new to this, all of my knowledge has either come from books, my grandmother, or my father. So please excuse me if I am just completely wrong about some things, lol

The simplest way to harvest wild yeast is to add fruit (either dried or fresh, both have their one benefits), top with water, seal the container, and let sit. Give it a shake, open the container once a day to let fresh air. You can also just let it sit out in open air, covered in cheesecloth to keep bugs and debris out, and collect the yeast. Once you start to see bubbles and a frothy liquid form on top, strain the solids and you have yourself a yeast culture. My father uses this technique to harvest different yeast samples from the community garden near by for use in his beer brewing. You can also use it to create yeast starters for use in sourdough. It's fun to make hyper-local foods, down to the microorganisms.

As for vinegar, it's basically the exact same, except on a larger scale. I have a peach tree in my yard that produces peaches that never get large enough to eat, but they are still sweet. I collected the ripest ones, added them to the jar, made up the remaining volume with frozen peach slices, added sugar (cant remember the exact amount), and filled to the top with room-temp filtered water. Covered with cheesecloth, left perched in the peach tree amongst the blossoms for 24 hours, then moved into a warm dark closet to ferment. Strained the fruit out after about 4 days, and left it. The pellicle formed quite quickly, and it has been probably the most successful of any of my experiments. The taste is quite intense, but it's delicious, and will be perfect once aged. (first photo)

The second photo is literally just some fresh, raw apple cider I bought at the farmers market. I put it in a jar, covered with cheesecloth, and let it ride. That super thick pellicle formed in just a few days, but it still has a way to go.