In accordance with embodiments of the present disclosure, systems and methods for determining a dynamic effective elastic modulus of a composite slickline or wireline cable are provided. A system for estimating the effective elastic modulus (or change thereof) may include a sensing head assembly, a vibration generator, a pair of pulleys, and an optical-based signal processing assembly. The system may detect a resonant frequency of a section of the composite cable held between the two pulleys and estimate the effective elastic modulus based on the detected resonant frequency variation. Adjustments for weight and length of the cable extending into the wellbore may be made as well to determine the dynamic elastic modulus of the cable. The opto-mechanical integrated system described below may enable real-time elastic modulus determination. The system may provide a non-contact inspection method for monitoring mechanical fatigue of a composite cable without interfering with the composite cable intervention operation.