Simulation of cavitation considering bubble dynamics is challenging due to the wide range of length and time scales. As the volume of fluid (VOF) method is suited for resolving the cavity and the discrete bubble model (DBM) in the Lagrangian frame is better for simulating micro-scale bubbles, the present work develops an Eulerian–Lagrangian multiscale cavitating flow solver with two-way transition in OpenFOAM. The growing and collapsing of discrete bubbles are solved using the Rayleigh–Plesset equation or the simplified Rayleigh–Plesset equation, and the adaptive mesh refinement is also available. Simulation tests of different cavitation conditions demonstrate the accuracy of the solver.