put a wooden crosspiece on the bottom potion of wall like in the picture, throw a grappling hook over the wall, secure grappling hook to the crosspiece, climb rope over wall.
Personally, I would remove the top section and sharpen all sides of the spikes and shafts that support them, then they is no securing a rope to the spikes and nobody climbing the wall can slide down the metal shafts. I would electrify the wall in sections activated by motion detectors.