[sumy23]

All measurement, but especially so at the quantum scale, involves interacting with the observed subject. One of the observations made by quantum mechanics is that you can't observe a system without interacting / altering it in some way.

To give you a macroscopic example, the way you detect the color of an object is to apply electromagnetic radiation in the visible light spectrum to the object and see which wavelengths are absorbed and reflected. The process of absorption and reflection is a physical interaction with the object you're looking at.