Lattice strain in crystals can be exploited to effectively tune their physical properties. In microscopic structures, experimental access to the full strain tensor with spatial resolution at the (sub‐)micrometer scale is at the same time very interesting and challenging. In this work, how scanning X‐ray diffraction microscopy, an emerging model‐free method based on synchrotron radiation, can shed light on the complex, anisotropic deformation landscape within three dimensional (3D) microstructures is shown. This technique allows the reconstruction of all lattice parameters within any type of crystal with submicron spatial resolution and requires no sample preparation. Consequently, the local state of deformation can be fully quantified. Exploiting this capability, all components of the strain tensor in a suspended, strained Ge1 − xSnx /Ge microdisk are mapped. Subtle elastic deformations are unambiguously correlated with …