The activities of spying and covert surveillance have surely been a fact of life since the dawn of civilisation, and probably even before that.
The use of the cuneiform pictographic/writing system, created by the Sumerians in the 4th millenium BC, involved the recording of information on clay tablets using a stylus. This was not a sophisticated method of noting information (although it was certainly that at the time) and must have been relatively time-consuming in comparison with later methods of preserving data such as pen and paper.
If a one Sumerian city-state wished to spy on another, how did the espionage agent get the required details back to his sponsor? Would he have merely remembered what he could, stolen the clay tablet he had read (which would have had its own disadvantages), or was there another way of so doing?
I can’t imagine the spy painstakingly copying information from one tablet to another and even if he had the time and opportunity to do this, the tablet would have been difficult to smuggle out because of its weight and the increased risk of discovery.