Here is an overview of the investigations conducted during the 2016 presidential race between Donald Trump and Hillary Clinton.
It seems that there was hacking during the campaign. You can visit the 2016 Hacking Fast Facts Presidential Campaign website for more details.
Special advocate Robert Mueller and many congressional committees are examining allegations of collusion between Russian agents and Trump associates during the presidential campaign and transition.
In July 2016, the FBI opened a counterintelligence investigation into possible links between the Russian government and the Trump campaigners.
Senate Special Committee on Intelligence - On January 13, 2017, the committee announced that it was conducting an investigation into Vladimir Putin's efforts to influence the US elections by assisting Trump against Clinton.
On May 17, 2017, Judiciary Committee of the Senate, asked the White House and the FBI to hand over all memos regarding the President's interactions with Comey, and to conduct a surveillance investigation into the dismissal of Comey, the committee held hearings on the Registration of Foreign Agents Act and attempted to influence elections.