Carlisle manager Gregg Abbott has taken four players on a week-long trial at Brunton Park.
Abbott will be monitoring the quartet during the players' first full week of pre-season training.
Patrick Clegg, 24, recently left Hibernian and has also played for Falkirk after starting out at Manchester United and fellow midfielder Billy Gibson, 19, from Watford impressed during a previous trial with the Cumbrians in May.
Another teenager, Jake Simpson, 19, won the young player of the year award at Shrewsbury last season before being released and Francois Zoko, 26, a former Ivory Coast Under-23 international, is currently at Belgian side KV Oostende.
Meanwhile, Carlisle are still considering the offer of compensation from Watford over the transfer of Tom Aldred.