Dear Mr. Ashokbabu12,
Deployment is an utilization of resource by the Client -- HR has the niche role to play while dealing with the Client as well the Candidate. Ensuring a "Tripartiate Agreement/Contract" signed between client, candidate and your firm will initiate a definite amount of scheduled communication. Necessary is the time-sheets prepared by the candidate signed by the authorised signatory sent you, will work the best. If not speak to the Client's HR requesting a monthly time (candidate's) report to be sent to you for further clarity and Invoice generation (if any) to be paid by the Client's position.
Additional documents required for the benefit Applicant's form, Non-competence agreement, Letter of Intent from the client etc., will serve your purpose on documentation process. Also, a copy of Appointment letter, Academic certificates and Experience/Releiving letter of the employee will you in safe records.