  Recent experiments using the quantum dot coupled to the topological
superconducting nanowire [M.T. Deng et al., Science 354, 1557 (2016)}] revealed
that zero-energy bound state coalesces from the Andreev bound states. Such
quasiparticle states, present in the quantum dot, can be controlled by the
magnetic and electrostatic means. We use microscopic model of the
quantum-dot--nanowire structure to reproduce the experimental results, applying
the Bogoliubov--de~Gennes technique. This is done by studying the gate voltage
dependence of the various types of bound states and mutual influence between
them. We show that the zero energy bound states can emerge from the Andreev
bound states in topologically trivial phase and can be controlled using various
means. In non-trivial topological phase we show the possible resonance between
this zero energy levels with Majorana bound states. We discuss and explain this
phenomena as a result of dominant spin character of discussed bound states.
Presented results can be applied in experimental studies by using the proposed
nanodevice.
