Every fingering that fits a hand
4212
moderate
421x
easy
4575
hard
xba8
easy
What is true of it
Bdim is B, D and F — 1, b3 and b5 counted from B.
The easiest of the 4 fingerings below is 4212: 4 fingers, held at the 1st fret.
None of them uses an open string, so this chord moves up the neck unchanged — the same shape 1 fret higher is the chord a semitone above.
Where its notes are on the neck
The brass dots are B, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
Bdim/D
x212
Bdim/F
x575
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.