  We report the influence of static mechanical deformation on the zero-field
splitting of silicon vacancies in silicon carbide at room temperature. We use
AlN/6H-SiC heterostructures deformed by growth conditions and monitor the
stress distribution as a function of distance from the heterointerface with
spatially-resolved confocal Raman spectroscopy. The zero-field splitting of the
V1/V3 and V2 centers in 6H-SiC, measured by optically-detected magnetic
resonance, reveal significant changes at the heterointerface compared to the
bulk value. This approach allows unambiguous determination of the
spin-deformation interaction constant, which turns out to be $0.75 \,
\mathrm{GHz}$ for the V1/V3 centers and $0.5 \, \mathrm{GHz}$ for the V2
centers. Provided piezoelectricity of AlN, our results offer a strategy to
realize the on-demand fine tuning of spin transition energies in SiC by
deformation.
