The England international has been seen as one of the major reasons behind United's success in the Premier League this season. His performances additionally saw him nominated for the PFA Player of the Year award, while he also made the PFA's Team of the Year.
When asked by the club's official website if he felt that he was playing the best football of his career, the 31-year-old replied: "Yeah. I feel like I've improved all the time I've been at United. You're always going to have better spells than others. That's natural and you can't be on an upward curve all the time or play at your best all the time."
However, Carrick added that he could still "improve" even further.
"As time has gone on I have improved as a player and I'm still looking to improve even now. You have to here," he said.
Carrick joined United from fellow Premier League side Tottenham Hotspur in 2006.