Voltage-induced magnetic anisotropy has been quantitatively studied in polycrystalline Ni thin film deposited on flexible substrate using microstrip ferromagnetic resonance. This anisotropy is induced by a piezoelectric actuator on which the film/substrate system was glued. In our work, the control of the anisotropy through the applied elastic strains is facilitated by the compliant elastic behavior of the substrate. The in-plane strains in the film induced by the piezoelectric actuation have been measured by the digital image correlation technique. Non-linear variation of the resonance field as function of the applied voltage is found and well reproduced by taking into account the non linear and hysteretic variations of the induced in-plane strains as function of the applied voltage. Moreover, we show that initial uniaxial anisotropy attributed to compliant substrate curvature is fully compensated by the voltage induced anisotropy.