Every now and then friends ask for an overview explanation of detection results from LIGO. I know/understand just enough to be useful to them.
One of the examples I use (I think it originated in a press pack from the group) is that the detection of the arm length changes is like measuring the distance to the nearest star to an accuracy smaller than the width of a human hair.
Now, pretty much anyone knows/can grasp how thin a strand of hair is, but the distance to the nearest star is not nearly as accessible.
Might there be a more generally accessible example like "detecting the sound of a single mosquito on the other side of Earth" where the everyman would have experience with the components involved?