How can you make the employee feel that he is constantly being monitored to do his job best?

Thanks for invitation,

By using " Balance Scorecard" evaluation and performance methodology.

By making KPIs which evaluate daily performance and accumulate monthly performance systematically.

Permanente monitoring is probably the worst tactic to reach your employee's top performance. Staff who feel the eye of the employer constantly upon them will always seek tricky ways to retaliate, as they see it as what it is: harassment. It is all about punishment vs incentive strategy: Managers need to devise a set of incentives to impose discipline, not by way of enforcing it, but by way of making it a profitable habit. 

Set a certain goal and provide them with an incentive: earlier lunch this Wednesday, 1hour late arrival next Monday or money bonuses, worked like magic. We had workers build a small housing complex 3 weeks earlier than calculated. It saved us money, time, and we managed to cherrypick the topmost performers for the next project. 

As a result of the daily and monthly development and professionalism, customer and reviewers, increase or decrease the Commitment

It is one of the way to squeeze best from an employ but at the same time there is a need to make him comfortable and give him freedom to do his job properly.