Once the implementation is complete, you can capture the data against the metrics you established in your project plan.
The methods you use will depend on the metric you developed.
For example, perhaps you have introduced a new process for completing a specific task. Having established a baseline of time taken to complete the task, you will need to collect data about how long the new process needs to complete the same task under the same condition.
Remember that users will need to understand why capturing the data is important, and they will also need skills and practice to develop the equivalent mastery to provide a real comparison between the baseline and the new situation.
Keep all the data and create a dashboard so you can analyse it and display it to others.
This is a great way to present the evidence of success, which is highly motivational for the team, the stakeholders, users and the executive.
It also captures necessary information for MLA so that they can report to the government on the outcomes of their funding.