  Tunneling spectroscopy is widely used to examine the subgap spectra in
semiconductor-superconductor nanostructures when searching for Majorana zero
modes (MZMs). Typically, semiconductor sections controlled by local gates at
the ends of hybrids serve as tunnel barriers. Besides detecting states only at
the hybrid ends, such gate-defined tunnel probes can cause the formation of
non-topological subgap states that mimic MZMs. Here, we develop an alternative
type of tunnel probes to overcome these limitations. After the growth of an
InSb-Al hybrid nanowire, a precisely controlled in-situ oxidation of the Al
shell is performed to yield a nm-thick Al oxide layer. In such thin isolating
layer, tunnel probes can be arbitrarily defined at any position along the
hybrid nanowire by shadow-wall angle-deposition of metallic leads. This allows
us to make multiple tunnel probes along single nanowire hybrids and to
successfully identify Andreev bound states (ABSs) of various spatial extension
residing along the hybrids.
