Widefield mid-infrared photothermal heterodyne (WIPH) microscopy enables sensitive and fast chemical imaging with high spatial resolution. The technique is realized using an external-cavity quantum cascade laser emitting and a digital frequency-domain lock-in filter for simultaneous multi-harmonic demodulation of WIPH signals recorded by individual camera pixels at a frame rate of 20 kHz. The filter allows the use of continuous-wave probe light and the time-resolved detection of photothermal decay curves. The microscope provides <1 µm spatial resolution in a 64x64 µm field of view. Here, we present preliminary results from hyperspectral WIPH imaging of alkyne-tagged palmitic acid (PA), azidetagged PA and perdeuterated PA via their absorption features in the cell-silent spectral region around 2100 cm-1. The alkyne and azide functional groups and deuterium are promising vibrational probes for selective imaging of biomolecules, such as lipids and proteins, in cells.