Ok but seriously they fund things like USAMTS which I assume gives them access to a list of promising young Americans.
That's boring maths though. Great, they found some people that can do hard maths. Cicada3301 winners prove they have a wide range of abilities. You're "tests" would be fine for the NSA types that just sit in a gov't cubicle going blind on cyphers. CIA wants people that can figure things out without getting caught.
https://www.cicada3301.org/
/s