Ml is a measure of volume. Inches is a measure of linear distance. The relation between them depends on how much volume you have per unit distance, as in a pipe or straw or eye dropper, for example.
A cubic inch is 16.387064 ml, so 4 ml is 4/16.387064 in^3, about 0.244 in^3.
A cubic inch is 16.387064 ml, so 4 ml is 4/16.387064 in^3, about 0.244 in^3.