A system, method and a non-transitory compute readable medium for evaluating a high aspect ratio (HAR) hole having a nanometric scale width and formed in a substrate, including obtaining, during an illumination period, multiple measurement results by an electrostatic measurement device that comprises a probe tip that is placed in proximity to the HAR hole; wherein multiple locations within the HAR hole are illuminated with a beam of charged particles during the illumination period; and processing the multiple measurement results to determine a state of the HAR hole.