This Letter presents the development of a low-cost polymer optical fiber (POF) sensor for mechanical wave monitoring. The POF is fabricated using the light polymerization spinning process (LPS-POF) with Bisphenol-A as its main component, resulting in a highly flexible fiber. The proposed LPS-POF sensor is applied on the assessment of squared waves with different amplitudes, where the amplitude and dynamic responses are compared to the ones of a piezoelectric transducer (PZT). In static conditions, a determination coefficient (R2) of 0.990 is obtained between the reference (PZT) and proposed sensors for the amplitude assessment of the wave. In dynamic analysis, the LPS-POF viscoelasticity is compensated using viscoelastic constitutive models, resulting in a R2 of 0.988 between the sensor responses, which indicate a mean error reduction of 21% when compared to the uncompensated responses in the amplitudes of different square waves. The dynamic analysis also shows the sensor capability of operating in frequencies as high as 25 Hz. Then, the sensor's responses, compared to the input squared wave, show the possibility of wave velocity measurement. Therefore, with a LPS-POF sensor array, it is possible to monitor these parameters in practical applications.