How do you contemplate delight you get due to action that leads to detachment? Let us follow the unbeaten track, the dukkha in right action. 

You see a man in need,  you feel compassion, wishing him well you help him with his worldly need, then you feel delighted of your action. 

Then you meditate the delight in your mind which arises due to the virtuous act you did, you contemplate it with the three mark of existence saying this delight is impermanent, it is born of external phenomena of a being in need of compassion, a being suffering and this feeling will end soon. If I hold this as mine and myself when it ends I will suffer, and this is dukkha.

Now let’s look at an action that is born of detachment.

You feel that you are attached to money, hoarding more than you need. You said to yourself, I have to let go of my attachment and to do so I will give all the excess I have and live in simplicity. 
You go out and give the money to those who need and put an end to your greed and hoarding. You feel delighted with your act, not that you helped someone, but because of your detachment… how do you contemplate this delight? Do you check it as above and hold it aloof not to grow big or do you nurture it to grow?
how do you contemplate this delight?

From MN1, we know that...


  MN1/en/bodhi ...delight is the root of suffering...


Therefore, rather than contemplating and nurturing delight, it may prove more fruitful to contemplate emptiness:


  MN8:3.6: A mendicant gives up and lets go of these views by truly seeing with right wisdom where they arise, where they settle in, and where they operate as: ‘This is not mine, I am not this, this is not my self.’


MN8 is a wonderful sutta that explores the relationship between practice and action that you have brought up in your question. Notice that what is contemplated is NOT delight:


  MN8:12.30: ‘Others will be stingy, but here we will be without stinginess.’