Abstract: Bell nonlocality, the strongest type of correlation in two-mode systems, is an indispensable resource for various quantum information science applications. However, a rigorous analysis of experimental data becomes difficult as the number of measurement outcomes increases, and traditional theoretical methods often fail for continuous observables. To address this, a necessary and sufficient condition for nonlocal correlations is proposed for systems where continuous measurements are performed on one part of the state and discrete measurements on the other. This condition is of particular interest for testing nonlocality in quantum optics.