  In recent years, it has been well understood that a Calder\'on-Zygmund
operator $T$ is pointwise controlled by a finite number of dyadic operators of
a very simple structure (called the sparse operators). We obtain a similar
pointwise estimate for the commutator $[b,T]$ with a locally integrable
function $b$. This result is applied into two directions. If $b\in BMO$, we
improve several weighted weak type bounds for $[b,T]$. If $b$ belongs to the
weighted $BMO$, we obtain a quantitative form of the two-weighted bound for
$[b,T]$ due to Bloom-Holmes-Lacey-Wick.
