Simpson hails from the Cumbrian town and played for the club towards the end of his career before becoming manager and guiding the Blues to successive promotions in 2005 and 2006, bringing League One football to Brunton Park.
The 48-year-old is looking forward to going back for the first-round tie on Monday night.
"When I saw that we were a seeded team and who were in the unseeded section, there was every chance it was going to be one of my ex-clubs and I have got to say I am delighted it is Carlisle," Simpson told the Derby Telegraph.
"It is my home town, the team I used to go and watch as a kid when we got to the heady heights of top of the old First Division. I was there watching in those days. And right up until I played for the Manchester City 'A team' on Saturday mornings, I used to be there every home game with my dad, stood on the Warwick Road End, so it will be nice to go back.
"It will be the first time I have been back since I left the club and I am looking forward to it."
Carlisle were relegated to League Two last season and began their campaign on Saturday with a home defeat by newly-promoted Luton.
However, Simpson insists Derby will not be underestimating the Cumbrians, who have beaten Blackburn and Ipswich in the League Cup in the past two years.
He said: "It is a tricky tie - it is never an easy place to go to. I went to watch them play Blackburn, so I know it is going to be tricky for us and it is a game that we need to prepare properly for."
The tie will also mean a return to Brunton Park for Derby skipper Richard Keogh, who spent two seasons with Carlisle from 2008 to 2010, while former Rams midfielder Paul Thirlwell plays for the Blues.
The sides last met in the League Cup in 1990, with Derby winning the second round tie 2-1 on aggregate over the two legs.