In many ways, the procedure for a probation revocation hearing is very similar to that of a full trial. However, the prosecution has an easier task in a revocation hearing than in an actual trial. Please note that the actual details of the procedure will vary from state to state.
When a person is charged with violating their probation, they are entitled to two hearings. The first is a preliminary hearing to determine whether there is probable cause to believe that they have actually violated their probation. At such a preliminary hearing, the defendant has the right to an attorney, the right to present evidence and witnesses, and some ability to confront the evidence offered against them. The witnesses are under oath and records are kept. The defendant is released if no probable cause is found but is kept in custody pending a final hearing if the judge finds probable cause.
If probable cause is found, there will be a final revocation hearing. The defendant has the same rights as in the preliminary hearing, though they do have an expanded right to confront witnesses against them. In the final hearing, the judge (both hearings are before judges, not before juries) has to find that a preponderance of the evidence shows that the defendant has violated their probation. This is a lower threshold than the “beyond a reasonable doubt” threshold needed to convict a person of a crime.
If the defendant is found guilty, the conditions of their probation may be modified. For example, they may have their freedom to move around limited, with that limitation enforced by electronic surveillance devices. Alternatively, they might have their term of probation extended. These are two options other than incarceration or a simple continuation of their previous sentence.