Question

How did British exploit the farmers

Answer 1

they forced the farmers to grow indigo in half of their land and they
have to give the grown indigo as a tax.

due to this most of the farmers suicided and when farmers tried to
explain the British that some farmlands are not suitable for cultivation
of indigo they threatened  to kill them

Answer 2

british take away the land of farmers.
they ask land revenue to farmers.
they beat them.
farmers were at lower levels.
farmers were treated badly.