A body can be charged in a process that does not involve charges coming to it from any other source. This is called charging by induction.
It can be done in the following way. Let’s assume that you want to charge a metal ball by induction. First, place the ball on an insulated stand. Now bring a charged object near it. This could be something like a plastic rod that has been rubbed on fur and is now negatively charged. When the rod is brought close to the metal ball, it repels negative charges and attracts positive charges in the ball. The negative charges then accumulate at the other end of the ball and can be removed by grounding them. Once that is done the ball is left with a net positive charged. And to do this we did not have to use up the charge in the plastic rod.
That is how a body can be charged by induction.