How to verify caches are actually being reused in ES

Hello. I want to know how I can confirm that filter caches are actually being used. I can't seem to find any API or documentation towards confirming the use of filter caches besides total memory and evictions, which doesn't really tell me much in this context. The reason I want to confirm is because running the same query w/ filters multiple times gives me the same perf result.

Try clearing the cache, run a test and then run it again and see if there is a difference?