He served in the Revolutionary War from 1779 to 1782 as a private in Captain Willis' Company, Colonel Brooks' Regiment, a unit of the Massachusetts Militia.

While owning and operating a farm, Fisk received his credentials as a Universalist minister and began to preach.

He was a delegate to the state constitutional convention in 1814, and served as judge of the Supreme Court of Vermont from 1815 to 1816.

[9] In 1817, Fisk was elected to the United States Senate to fill the vacancy caused by the resignation of Dudley Chase.

He served from November 4, 1817, until resigning on January 8, 1818[10][11] to become U.S. collector of customs for the district of Vermont.

He served from 1818 until 1826,[12] moved to Swanton, Vermont, in 1819 so that he could be closer to the border with Canada and the crossing points where customs were paid.