The new Spain cap left Barca for Dinamo as a teen and has played his way into La Roja's Euros plans.
Mundo Deportivo says Barca are now exploring the prospect of re-signing Olmo. The Catalans have been watching the youngster weekly.
Playing at wing-back, Olmo has scored six goals and made six assists in 19 games for Dinamo this season.
Along with scouting the 21 year-old, Barca are also in contact with Olmo's agent Juanma Lopez every 8-10 days.