He is former owner of Zaun's Hardware and Vice President of R&R Realty Marketing Group, and received his Bachelor's degree from Grand View College.

In January 2017, Zaun proposed a bill to end tenure in public universities in Iowa.

[3] After Republican Tom Latham of the newly-redistricted 3rd congressional district announced his retirement, Zaun ran to succeed him.

On July 4, Zaun voiced his disappointment and suggested he would leave the Republican Party, leading some to encourage him to run for the seat as an Independent.

The Des Moines Police Department confirmed that the gun was found on the Republican senator during his screening.