Well, for example, I could set up a camera to take a picture when nobody is around. That picture would show the existence of something when nobody is around. Nobody need to know about the existence at the time the picture is taken.
And this is something that is quite common: for example, to take pictures of wildlife in this way. No person needs to see the actual animal, but the camera takes a picture which shows the existence of that animal at a particular time.
Take #2:
Here is the test as per random. You can build a camera that takes picture of wild animals on a wild animal trail in nature. Now the camera also takes a picture when there is no animal each time it has taken a picture with an animal.
So say there are 50 picture and the camera mixes the order randomly.
Now without looking at a given picture, tell if there is an animal in it or not. So what does the picture show the existence of?
Now there is something, but you don't know what it is. That is the point.
You can using ccogntive understanding give reasin of that there is unknown element to the world. That what that is other than unknown, is unknown.
That is the point of independent of the mind.