  We present here the straightforward implementation of pump-probe methods into
existing scanning tunneling microscopy (STM) systems. Our method uses the
waveform-sequencing abilities of a standard arbitrary waveform generator (AWG)
and a simple mechanical relay switch that either connects the regular STM
control electronics or the AWG to the STM system. Our upgrade further enables
pulsed-ESR excitation for advanced STM based spin-resonance experiments. We
demonstrate the technical implementation, signal detection using a lock-in
amplifier, and cross-correlation measurements of DC/DC and DC/RF pulses
highlighting our ~5 ns time resolution, here limited by the speed of the
available electronics. Our setup is highly versatile and can be extended to
suit other needs of STM based investigations such as required in diverse
mapping schemes or the coherent manipulation of qubits.
