Apple introduced a nice feature:
In short: every single local search in spotlight is sent to Cupertino. That includes of course search for a file, person, company, etc. Nice.
It is not a secret function, because it is mentioned in the Yosemite’s licence:
http://www.theregister.co.uk/2014/10/20/apple_spotlight_privacy_qualms/
You can disable it if you like: https://fix-macosx.com/