Long-range angular correlations between particles have the potential to reveal physics beyond the Standard Model, such as Hidden Valley scenarios. The focus is on a hidden QCD-like sector, where the production of HV matter alongside QCD partonic cascades may enhance and extend azimuthal correlations among final-state particles. This study, conducted at the detector level, investigates the detectability of such signals at future $e^+e^-$ colliders, which provide a cleaner experimental environment compared to the Large Hadron Collider (LHC). In particular, unexpected structures in the two-particle correlation function could suggest the presence of new physics.