Disclosed embodiments include a distributed nondestructive inspection method and system for slickline cable structural defect and mechanical strength degradation inspection. One method may include transmitting a light pulse along an optical fiber embedded in a slickline cable. A reflected light signal is received from the optical fiber in response to the local strain induced refractive index variation. Defects and mechanical strength degradation may be determined by time-dependent time-domain and frequency-domain data analyses of the dynamic strain signals and power spectral density variation as a function of time and cable location.