Recent studies have proposed that the nuclear millimeter continuum emission observed in nearby active galactic nuclei (AGN) could be created by the same population of electrons that gives rise to the X-ray emission that is ubiquitously observed in accreting black holes. In my talk I will present the results of several dedicated high spatial resolution (~60-100 milliarcsecond) 100 GHz ALMA campaigns focussed on nearby radio-quiet AGN. We find an extremely high detection rate (~95\%), which shows that nuclear emission at mm-wavelenghts is nearly ubiquitous in accreting SMBHs. This emission is extremely variable on short timescales, confirming the idea that it comes from a very compact region. Our high-resolution observations show a tight correlation between the nuclear (1-23 pc) 100GHz and the intrinsic X-ray emission. This shows the potential of ALMA continuum observations to detect heavily obscured AGN (up to an optical depth of one at 100GHz, i.e. ~1e27 cm^-2), and to identify binary SMBHs with separations <100 pc, which cannot be probed by current X-ray facilities.
