Fabeck was born in Berlin in 1854, when it was the capital of the Kingdom of Prussia.
On 24 October 1887 married Helene von Seldeneck (born 7 October 1863 in Karlsruhe, † 13 July 1938 in Cologne), the daughter of the Grand Duke of Baden, chamberlain of William and Julie Brandt Seldeneck of Lindau.