  We demonstrate novel implementations of high-precision optical magnetometers
which allow for spatially-selective and spatially-resolved in situ measurements
using cold atomic clouds. These are realised by using shaped dispersive probe
beams combined with spatially-resolved balanced homodyne detection. Two
magnetometer sequences are discussed: a vectorial magnetometer, which yields
sensitivities two orders of magnitude better compared to a previous realisation
and a Larmor magnetometer capable of measuring absolute magnetic fields. We
characterise the dependence of single-shot precision on the size of the
analysed region for the vectorial magnetometer and provide a lower bound for
the measurement precision of magnetic field gradients for the Larmor
magnetometer. Finally, we give an outlook on how dynamic trapping potentials
combined with selective probing can be used to realise enhanced quantum
simulations in quantum gas microscopes.
