Simultaneous assessment of cellular scaffold structures and traction forces across multiple wide spatiotemporal scales is essential in mechanobiology, which is hindered by the limitations of conventional imaging techniques. Here, we propose using exploiting optical diffraction tomography of embedded microparticles for a label-free, volumetric, and high-speed assessment method of cell morphologies and traction forces. The proposed approach enables quantitative spatiotemporal analyses of cell migration dynamics and immunological synapse kinetics, by providing cell protein densities and membrane traction force distributions at 140 nm lateral, 400 nm axial, and 1 Hz temporal resolution.