Pacheco, 28, recently was designated for assignment and then placed on outright waivers by Colorado.
Pacheco is known for his defensive versatility and contact skills. He has seen significant time at catcher, third base and first base with the Rockies.
In 2012, Pacheco posted a .309/.341/.421 triple-slash in 505 plate appearances. Those numbers could be intriguing to the Diamondbacks, who are getting a .194/.215/.306 line from current backup catcher Tuffy Gosewisch.
Pacheco, however, owns a .238/.282/.320 line the last two seasons.
To make room for Pacheco, the Diamondbacks designated for assignment infielder/outfielder Nick Evans.
After Cahill was designated for assignment on Monday he has the option of accepting a minor-league assignment or becoming a free agent. Cahill will start tonight for the Rawhide.