  We study the response of diquark wave function in \Lambda-type baryons to
strong magnetic fields. It is found that quantum state of J=0 diquark (ud) in
the magnetic field changes due to magnetic polarizability, and constituent
quarks in (ud) diquark become polarized. The phenomenon influences polarized
quark distribution functions \Delta u(x) and \Delta d(x), which therefore may
be sensitive to the internal electromagnetic fields in hypernuclei. We also
speculate, that strange quark polarization in nucleon may originate from the
interaction of virtual (ss') quark pairs with the intrinsic magnetic field of
nucleon B $\approx$ 10^13 T.
