How to measure satisfaction level of the customers?

The following methods can be used to measure customer satisfaction.

1. Surveys to Measure Overall Satisfaction

Overall satisfaction can be measured through a survey conducted from your customers after they finished the purchase process.

2. Objective Measurement Approach For Loyalty

Loyalty can also be measured via a survey after the purchase process, it is however more powerful to measure the actual behaviour than the intention.

3. Apps for Attributional Satisfaction

4.Determining the Goals of Your Analysis.

5.Consider qualitative and quantitative approaches. 

• Ordinals - who believes that we can rank the good according there utility

In Economics there are two approaches

• Cardinal - who believe we can measure the utility in term of units 
• Ordinals - who believes that we can rank the good according there utility

Post sales communication that can be done through a phone call or a survey, most customers will ignore that request, so you need to add incentives so customers will have something to look forward to. 

It depends on the products.  So of them you can have the feedback from the customers by phone or social media. Some of them during regular meantinance you.  Sales income is a clue that the customer satisfy or not also the meantinance request is another clue.