She later attended Villa Julie College, where she earned a Bachelor of Science degree in information systems in 1994, the Community College of Baltimore County, receiving an associate degree in early childhood development in 2010, and the Notre Dame of Maryland University, where she received a Bachelor of Science degree in early elementary education in 2021.

[1] McCaskill is the vice president of the SEIU Local 500 labor union, which represents teachers, child-care professionals, and part-time college faculty in Maryland and Washington, D.C.[3] She previously served as the leader of the union's bargaining committee and as the chairwoman of its Committee on Political Education (COPE).

[6][7] In November 2017, McCaskill graduated from Emerge Maryland, a group dedicated to training and electing Democratic women to office.

She came in second place alongside incumbent Sheila Ruth, receiving 23.0 percent of the vote in the Democratic primary.

[14] During the 2016 Baltimore mayoral election, McCaskill canvassed for then-mayoral candidate Catherine Pugh, motivated by her support for a bill to raise the city's minimum wage to $15 an hour by 2022.