Basically the other day I left my macbook unattended at a coffee shop while I stepped out for a smoke. I feel as if I had something exfiltrated from it while I was outside. To cure my paranoia, I am making this question on due part. Can anyone tell me how I can view some kind of history or log file under OSX El capitan (if there is any) that can show me all USB devices that were connected to my macbook during a certain time or date?
Mounting and unmounting a USB disk should be logged in the log files. You can use the
Console app to search through the logs.
Also, teach yourself to always lock your screen with a password when leaving the keyboard.