I just saw a website a few days ago which includes this effect. I tried to recreate the website and saw the noise effect. Nothing crazy and special but it is nice to see and enjoy the effect. I am using a GIF file that includes a lot of noise. Using CSS I tried to make the effect easy to see and watch.There are also few svgs that I used to create a moving SVG effect .Please ignore the button or any other text and image of the website because I also don't know what I have done but but it looks great.

Have fun and enjoy the website