The former Wigan Athletic midfielder arrived in the summer.
"I'm loving life here and the fans have been brilliant to me," McCarthy said to evertontv. "I always believed I could come here and play games. You need to have a bit of that in you, to be honest, to go and prove you can go and play for a club the size of Everton.
"I knew it wasn't going to be easy and that it would be tough, and I had to bide my time at first to get into the team. It's brilliant to be playing.
"At first it was tough because it was a lot of money, to be honest. Obviously the gaffer believed in me though, came back to Wigan for me and paid the money.
"When I came here I wanted to prove that I could play in front of good fans for a massive club. I just need to keep working hard on and off the pitch because there is still a long way to go."
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