Does My Mac Have A RAT FILE?

Hi, I am new to this kind of stuff 😀, So I might not give the sufficient information you need to find the answer to my question. Sorry! Anyway lets get to the point! I have a Mac Air and it is like 5 months old. I have been hearing about the rat file hacks and the trojan horses and all of those hackers who try to get personal information. I do not have any thing in my mac for personal information except iTunes and thats it. Im just worried that people are watching me through my webcam ( BUILT-IN). It doesn't show a green light and theres a 75% It is not hacked but i am just making sure! I have no suspicious activity, so in the comment please tell me some details and signs of my device being hacked! I am running on Mac Yosemite OS X Or something like that - and i don't have any programs installed except Minecraft 😀. So please tell me what the signs of a hacked mac computer and If people are using my webcam 😀 ! Thank you very much! Sorry to waste your time if it is not hacked and I'm just in a panic frenzy but please help me out here 😀 I searched everywhere and couldn't find symptoms and/or signs! ( MY MOUSE DOES NOT MOVE FROM DIFFERENT PLACES EITHER )!