Cahill, who continues to struggle with a persistent foot injury, revealed how former crowd favourite Ferguson, who was paraded on the Goodison pitch before kick off, set him the perfect example to become another Toffees' icon.
He said: "It's fantastic. He's one of my heroes and he's the reason why I got 13 goals in my first season here and we finished fourth.
"I had chat with him last week, and it's about keeping the spirit and the dream alive. The dream here is that we have so many good players but we have to keep believing. In the end that belief came against Manchester City.
"I'm happy to be on the bench and coming on because three weeks ago they'd written me off and said my season was over. Yes I take a massive risk playing but it's worth it on days like Saturday."
Cahill is renowned for his aerial prowess, but the 31-year-old joked that heading was one of the few things he did not look to Ferguson for help with.
"I always used to make jokes about Fergie that the only thing he couldn't do was head a ball," he said. "He was an exceptional talent. The best thing I learned from him was about discipline, attitude and work ethic in training.
"He taught me what it means to play for Everton and it's priceless. I try to be the same example he is as a footballer and a person because he's a gentleman."