Neutron noise denotes small time-dependent fluctuations of the neutron flux around its stationary value, typically induced by perturbations in the reactor core. These perturbations may originate from changes in coolant density, vibrations of fuel assemblies or control rods, and other mechanical or operational effects. In power reactors, neutron noise can be monitored through in-core and ex-core detectors for diagnostics, anomaly detection, and operational surveillance. This thesis investigates the non-perturbative Monte Carlo formulation of neutron noise in the frequency domain and benchmarks it against the standard, or orthodox, linearised approach. All simulations were performed with the Monte Carlo mini-app MGMC, developed at CEA, which supports both linear and non-perturbative neutron noise calculations.