All organizations have dual oversight system, internal and external. Internal falls under the realm of managerial control and external is generally by the policy making body. We find oversight both in business sector organizations and public sector organizations.
The US Federal Government took decisive measures to strengthen internal oversight albeit internal control (following large scale abuses in the 1980s and 1990s) with reporting to oversight authorities such as the SEC., after the accounts and control systems are vetted by professional external audit authorities. Standards are set by professional organizations such as GAAP.
Difference between internal and external audit:
Some well known external audit oganizations, which in fact do more than audit:
Interesting combination of subjects: https://www.ucop.edu/ethics-compliance-audit-services/audit/resources/external-audit-organizations.html
Good education track for business sector oversight jobs are MBA, MBA (Finance) and MAFM: https://www.keller.edu/graduate-degree-programs.html
Public sector organizations are subject to elaborate oversight both internal and external. Most federal departements and agencies have an office of inspector general albeit IG.
Principles and standards: https://www.cabq.gov/audit/documents/OIGStandards-Greenbook.pdf
On the external side, the US General Accounting Office is now the General Accountability Office whose work complement those of the IGs and helps the legislative bodies in their external oversight responsibility.
More on internal control:
Guide to internal control: https://www.thecaq.org/guide-internal-control-over-financial-reporting
Management responsibility for internal control: https://obamawhitehouse.archives.gov/omb/circulars_a123_rev
The best education for public sector oversight jobs:
MPA at John Jay College, City University
I taught several courses for the MPA at John Jay College for several years, both the Management track and the Oversight track. I helped develop the concentration on International Oversight based upon my experience at the UN Office of Internal Oversight Services. I undertook training at the US Government Accountability Office i.e. the US-GAO. I highly recommend the John jay MPA in Inspection and Oversight, a great career track not so well known and thus not so crowded..
MPA Inspection and Oversight, John Jay College
MPA Program in Inspection and Oversight
The mission of the Master of Public Administration in Inspection and Oversight Program at John Jay College of Criminal Justice is to prepare students for public service careers in inspection and oversight organizations and to advance the study of Public Administration through scholarly and applied research and community service. The program seeks to inspire students to the highest ideals of citizenship and public service, reinforced by a commitment to accountability, transparency, and equity. The program offers students opportunities to acquire professional and political knowledge and skills, based on academic studies, public service experience and partnerships with faculty in scholarly endeavors.
The program offers specializations in Forensic Accounting, International Inspection and Oversight, Investigation and Operational Inspection, Organizational Assessment and Monitoring, Law and Inspection and Oversight, and Independent and Contractual Inspection and Oversight.
The programs share common foundation courses, and a student admitted to one program can transfer to the other program without special approval or application fees.
The programs are offered in several formats and venues.