The standard grips this chord is usually shown with.
BbmMaj9 is Bb, Db, F, A and C — BbmMaj7 with the ninth added on top.
It sounds the same unease with more colour over it. The ninth softens the edge without resolving anything.
Minor tonic — melodic minor, extended.

| Bb | Db | F | A | C |
|---|---|---|---|---|
| 1 | ♭3 | 5 | 7 | 9 |
Also written BbmM9, Bbm(maj9) or Bb-Δ9. The same chord either way; which spelling you meet depends on who wrote the chart.
BbmMaj9 in 2nd inversion puts F in the bass instead of Bb, the 5th of the chord. The notes are the same; what changes is what the bass line does, which is most of why you would reach for it — it lets the lowest voice move by step where the root would have jumped.
One of BbmMaj9’s 6 common shapes does this:143211
Play BbmMaj9 as a shell — root, third and seventh — and the spare string takes the 11 (Eb) or the 13 (G).
All 6 common shapes as fret numbers, lowest string first. Hover or tap one to see it drawn.
How you get to it. The turn that lands on BbmMaj9 is Cm7♭5 to F7♭9: the ii and the V of Bb minor, which is where a minor tonic is usually arrived at rather than simply begun on.
Every note of BbmMaj9 is in Bb harmonic minor and Bb melodic minor.
Change one note of BbmMaj9 and you have Bbmaj9 (the minor third becomes the major third), Bbm69 (the major seventh becomes the sixth), Bbm9 (the major seventh becomes the flat seventh), BbmMaj7 (drop the ninth), BbmMaj11 (add the eleventh) or Bbmadd9 (drop the major seventh).
BbmMaj9 is a minor chord — root, minor third, fifth. Minor chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.