Astrophysical candidate sources of ultra-high energy cosmic rays inevitably produce high-energy neutrinos in and/or around them. While cosmic rays are scattered in the inter-galactic magnetic fields, neutrinos point back to their origin. Hence neutrinos can be used to probe astrophysical sources just like in usual photon astronomy. Here we present the expected neutrino signals from different astrophysical objects and discuss their possible applications to study these intriguing sources.