Hi there! The closest serious transportation hub to Carlisle is Lowell, MA. That said, there are a number of "park & rides" near you and also Waltham has a commuter rail stop, depending on where you live in Carlisle. Luckily for you, Lowell is both close by and would also give you a reverse commute, allowing you to avoid a lot of traffic!
Here is a link to the train map for the greater Boston area. http://www.mbta.com/schedules_and_maps/rail/
Looks like the closest train stop is West Concord and the closest bus stop is at the Bedford VA. The MBTA link is filled with commuter information and is worth a look.
In most of the towns surrounding Carlisle there is transportation- Concord, Westford, Bedford, Chelmsford, Acton. Concord, West Concord and Billerica all have MBTA stops, most about 5 miles from Carlisle. However Carlisle itself does not have mbta transportation.
Let me know if I can help you with additional information .