and, in particular, to their use as quantum simulators. A key challenge in this effort has been the identification of the quantum states realized by these circuits. Here, we propose a probe circuit capable of reading out many-body correlations in an analog quantum simulator. Our measurement scheme, designed for many-photon states, exploits the non-linearity of the Josephson junction to measure two-point (and potentially higher-order) correlation functions of the superconducting phase operator. We demonstrate the capabilities of this design in the context of an LC-ladder with a quantum impurity. The proposed probe allows for the measurement of inherently quantum correlations, such as squeezing, and has the potential to significantly expand the scope of analog quantum simulations using superconducting circuits.