A darcy is a measure of how permeable something is, or how easy it is for liquid to flow through a seemingly solid object. It is considered a metric measurement, but it is more commonly replaced by square meters. Once you convert over to meters, you can convert the value again to micrometers, which were once represented by a symbol called a micron. Micrometers used to be called microns, too, but the U.S. Metric Association says that label was "officially eliminated" in 1968.
Multiply the darcy value by 0.98692 x 10^-12, or 0.00000000000098692. This gives you the value in square meters. If you have 2 darcies, 2 x 0.98692 x 10^-12 gives you 0.00000000000197384m^2.
Convert the meters squared to micrometers squared by moving the decimal point to the right by six spaces. In this example, the awkward 0.00000000000197384m^2. becomes 0.00000197384 micrometers^2.
Convert the micrometers back to darcies by converting first to meters -- reverse the decimal point six spaces to the left -- and dividing by 0.98692 x 10^-12.