The illegal and unethical theft of business secrets for use by a competitor to achieve a competitive advantage is known as

Industrial espionage refers to the illegal and unethical practice of spying on a competitor to obtain trade secrets, intellectual property, or other confidential business information. The primary goal is to gain a competitive advantage through methods such as bribery, technological surveillance, or theft of physical or digital assets.

• Sabotage involves the deliberate destruction or damage of a competitor's physical assets or operational processes.
• Subversion is the attempt to transform or undermine the established social order or power structures of an organization or state.
• Counter-intelligence refers to actions taken to protect an organization's own secrets and thwart the espionage efforts of others.

Because the question specifically describes the theft of secrets for competitive gain, industrial espionage is the correct term.