In one-dimensional Luttinger liquids the interaction strength is determined by the Luttinger Parameter K. It proves proves difficult to be measured, as it is usually hidden in power-law dependencies on temperature or bias. In this talk I will propose a setup, which allows a dynamical measurement of this parameter. In this talk we will, based on an equation of motion description of Luttinger Liquids, discuss a setup with a capacitive gate, which allows to probe the interactions directly. In this setup, an expression for the frequency dependence of the conductivity can be obtained, from which we can extract K directly and from a low frequency expansion. Furthermore the influence of the precise form of the change in interactions at the contacts is examined using the formalism. As a perfectly suited system to test the predictions, we will shortly discuss helical edge states of topological insulators.