We report the design of reconfigurable metamaterial consisting a large array of nanowire featuring U-shaped cross section. These nanowires, also named as nano-scale metamolecules, support co-localized electromagnetic resonance at optical frequencies and mechanical resonance at GHz frequencies with a deep-sub-diffraction-limit spatial confinement (~λ2/100). The coherent coupling of those two distinct resonances manifests a strong optical force, which is fundamentally different from the commonly studied forms of radiation forces, gradient forces, or photo-thermal induced deformation. The strong optical force acting upon the built-in compliance further sets the stage for allowing the metamolecules to dynamically change their optical properties upon the incident light. The all-optical modulation at the frequency at 1.8 GHz has thus been demonstrated experimentally using a monolayer of metamolecules. The metamolecules were conveniently fabricated using CMOS-compatible metal deposition and nano-imprinting processes and thus, offer promising potential in developing integrated all-optical modulator.