Noun phrases encoding

How to encode all the noun phrases of a sentence to create a feature for a classification problem?

sentence- This makes a lot of the questions asked in this paper extremely relevant to the field
Noun phrases: [‘a lot’, ‘the questions’, ‘this paper’, ‘the field’]

I have to create a feature like
sentence feature
sentence1 feature_vector1
sentence2 feature_vector2

How to encode all the noun phrases of a sentence to create a feature for a classification problem?