Acker, 26, is a former sixth-round pick of the 49ers back in 2014. San Francisco traded him to the Chiefs at the start of the 2016 season for a 2018 seventh-round pick.
Acker played out the final year of his four-year, $2.340 million rookie contract before signing on with the Colts last month.
In 2017, Acker appeared in all 16 games for the Chiefs and recorded 23 tackles, one interception and a pass defense.
McDougle, 27, is a former third-round pick of the Jets back in 2014. The Jets waived him coming out of the preseason last year and later signed him to their practice squad. New York eventually promoted McDougle to their active roster in November.
The Eagles acquired him from the Jets in exchange for S Terrence Brooks during the preseason.
McDougle was entering the final year of his four-year, $2,863,876 contract and set to make a base salary of $705,000 for the 2017 season when the Eagles signed him to a one-year extension through the 2018 season. However, Philadelphia later reversed course and waived McDougle.
McDougle had a brief stint with the Saints last season.