We demonstrate the fabrication of a 3D polymer/glass micromechanical sensor by combining two femtosecond laser direct writing processes: subtractive laser-assisted chemical etching combined with additive two-photon polymerization techniques. In the first step, the micromechanical sensor was fabricated from a single fused silica substrate by selective laser etching technique. The mechanical parameters of the glass are well-researched, thus it could be used to investigate unknown polymer mechanical properties through the concept of coupled-system. In the second step, we directly integrate polymeric beam via two-photon polymerization. This combination of additive and subtractive techniques allows investigation of reversible deformations of polymeric microstructures upon immersion in various solvents. Furthermore, we demonstrate that Young's modulus of these laser fabricated structures could be altered by changing the writing laser exposure dose, also influenced by surrounding solvent.