Doppler shift is also referred to as the radial velocity method. In this method, the distances between objects in the space can be measured quite accurately. Since Doppler shift relies on electromagnetic radiations, the phenomena is quite accurate and hence can be used to measure distances with great precision.
For instance, when an object is moving away from the earth, it appears red. This is due to Doppler shift. The distance of the object from the earth at any point can be calculated by measuring the light that we receive. This light would be observed at a longer wavelength than usual.