An electrostatic voltmeter is a kind of tool that helps you measure how much electric power is in something. Think of it like a ruler that helps you measure how long something is, but instead of measuring length, it measures electricity.
This tool has two important parts. One is a plate that has a lot of tiny hairs or fingers sticking out of it. The other part is a small metal ball that can move around. When you put the tool near something that has electricity in it, the tiny hairs on the plate get really excited and start to wiggle around just like when you run your fingers through your hair...only the hairs are much smaller.
This movement pushes the metal ball around, and the more electricity there is, the harder the tiny hairs wiggle, and the farther the metal ball moves. This helps you know how much electricity is in the thing you are measuring.
So, using an electrostatic voltmeter means you can figure out how powerful the electricity in something is by how much it makes the little metal ball move. It’s important to detect electricity accurately, especially when it comes to working with electronics or building something that needs electricity to work.