The French left back was named as part of Barca's squad for their pre-season tour of the United States, but the club has granted him permission to leave their camp and return to Europe in order to work on his move to Goodison Park.
"Lucas Digne travels today to Barcelona with the Club's permission to finalise his departure from the Club," the Catalan side posted on Twitter on Sunday evening.
Barca and Everton are reported as having agreed over a €22m fee and a further €3m in add-ons for the 24-year-old, according to Goal.
Digne, who moved to the Camp Nou in 2016, has found opportunities limited under Ernesto Valverde and missed out on the World Cup as a result of not being played consistently.
He will hope to reignite his career at Goodison Park next season, with the Toffees set for a transitional period having hired former Watford boss Marco Silva this summer.