The England international said conversations with Mackay convinced him to leave White Hart Lane despite 26 starts in all competitions last season.
"His influence was massive," Caulker told Sky Sports News. "I spoke to Malky a couple of days ago and everyone's given him a glowing reference, so I'm looking forward to working with him.
"As soon as I heard about the move, I was really excited to come, hopefully play a lot of games and have a good season.
"Regardless of what team you're at you have to work hard and there's good competition for places as I've seen this morning. I'm going to work hard and I'm looking forward to the new challenge."