Very-low-mass stars are exhibiting strong magnetic activity and variability. The direct measurement of magnetic flux, however, is very difficult because of the poor visibility of Zeeman-sensitive atomic spectral lines. Molecular lines, on the other hand, are problematic because Zeeman splitting is often poorly understood. Indirect evidence through radio observations and strong emission lines suggest very strong magnetic fields. In some early-M dwarfs, Zeeman Doppler maps are also available. At present, the only way to directly measure magnetic flux in very-low-mass stars is an empirical comparison of molecular absorption lines to spectra of early-M dwarfs with magnetic flux measured in atomic lines. This method was applied to about 30 objects so far. I will summarize the current status of magnetic field measurements in very-low-mass stars and show potential ways to measure magnetic fields in brown dwarfs.