The Relationship Between Environment and Genetic Change

The question is how do we understand the relationship between environment and genetic change? So if there's a change in phenotype that could be driven by genetic change or environmental change or a combination of both. How do we sort of describe that in evolutionary terms? Like if we're focused on evolution is change in allele frequencies then it seems that at least sort of naively well one way that I would describe that is simply to say that there could be different causes of changes in frequency.