Penning traps are extremely powerful and versatile tools for high precision physics. This enormous impact is mainly based on the fact that in the magnetic field B of the trap the free cyclotron frequency of a trapped particle can be measured with high fractional precision. We invented a novel method to measure the free cyclotron frequency of a single trapped proton in one shot. The method is based on double-dressed states. By application of frequency modulated sideband drives the double dressing is produced, and energy is transferred between all eigenmodes of the trapped particle. From the measured Fourier Spectrum all eigenfrequencies are obtained. We report on this novel technique in Physical Review Letters