The method to detect and determine the profile of the material property or the structure changes not only on surface but also at the subsurface, of a storage medium or a scanned sample. This method comprises the following steps: (a), a nondestructive periodic or modulated perturbation is applied to the sample to be scanned. (b) the perturbed sample is then scanned using a microprobe, e.g., scanning tunneling microscopy (STM) or atomic force microscopy (AFM), which is responsive to the applied periodic or modulated perturbations and (c) the modulated output signals from the microprobe, in combination with the input perturbation signals, are processed and demodulated to automatically control the motion of the probe, and to determine the profiles of the material properties or the structure changes of the scanned sample.