An auxiliary measuring instrument, configured to form together with a ground-based surveying device having range-and-direction measuring functionality, a system for surveying or staking out object points, wherein the auxiliary measuring instrument including a handheld main body of a defined length, and a man-machine interface, wherein the auxiliary measuring instrument is designed in a pen-like form and size and is configured to aim at an object point to be surveyed or staked out in a one-handed manner with a first end of the auxiliary measuring instrument and wherein a body is attached at a second end of the auxiliary measuring instrument, wherein the body is designed for optical-image-based determination of the position of the auxiliary measuring instrument by the surveying device.