The search for substellar companions to subdwarf B stars in connection with evolutionary aspects The formation and evolution of single hot subdwarf B stars is not entirely understood. Enhanced mass loss during the red giant phase is a prerequisite to explain the very existence of these stars yet its cause is a matter of debate. One hypothesis predicts that substellar companions like brown dwarfs and exoplanets may be able to have a decisive influence on the formation and evolution of single subdwarf B stars. This dissertation investigates two pulsating subdwarf B stars with the goal to search for substellar companions and to directly measure the evolutionary timescales. The long term multi site photometric data were taken in the framework of the EXOTIME (EXOplanet search with the TIming MEthod) program and cover a baseline of several tens of months. The secular behaviour of several pulsations in each target is investigated by applying a timing method and constructing O C (Observed minus Calculated) diagrams. The analysis results in the fundamental insight that both targets are in a phase of global expansion that their pulsation periods increase on a timescale of several million years and that the two target stars have probably already undergone core Helium exhaustion. Furthermore the O C diagrams show evidence for the presence of substellar companions. The star HS0444+0458 has a brown dwarf companion candidate of roughly 31 Jupiter masses in an orbit of 0.27 astronomical units. An exoplanet candidate of 5.6 Jupiter masses is found to orbit its host star HS0702+6043 at a distance of 1.15 astronomical units. These detections provide a direct support for a formation channel of single subdwarf B stars that includes substellar companions as the mass loss trigger.