  Type Ia supernovae arise from thermonuclear explosions of white dwarfs
accreting from a binary companion. Following the explosion, the surviving donor
star leaves at roughly its orbital velocity. The discovery of the runaway
helium subdwarf star US 708, and seven hypervelocity stars from Gaia data, all
with spatial velocities $\gtrsim 900$ km/s, strongly support a scenario in
which the donor is a low-mass helium star, or a white dwarf. Motivated by these
discoveries, we perform three-dimensional hydrodynamical simulations with the
$\texttt{Athena++}$ code modeling the hydrodynamical interaction between a
helium star or helium white dwarf, and the supernova ejecta. We find that
$\approx 0.01-0.02\,M_{\odot}$ of donor material is stripped, and explain the
location of the stripped material within the expanding supernova ejecta. We
continue the post-explosion evolution of the shocked donor stars with the
$\texttt{MESA}$ code. As a result of entropy deposition, they remain luminous
and expanded for $\approx 10^{5}-10^{6}$ yrs. We show that the post-explosion
properties of our helium white dwarf donor agree reasonably with one of the
best-studied hypervelocity stars, D6-2.
