curl --request GET \
  --url https://api.hubapi.com/integrations/v1/{application}-id/timeline/event/{event}-type-id/{event}-id

"\nThe following is an example of data retrieved for an event with no extra data and no custom properties:\n\n{\n  \"id\":\"3\",\n  \"applicationId\":123456,\n  \"portalId\":12345678,\n  \"eventTypeId\":123,\n  \"objectType\":\"CONTACT\",\n  \"objectId\":1,\n  \"extraData\":null,\n  \"timestamp\":1416852689573\n}\n\nFor an event with extra data and custom properties, this would be a valid response.\n\n{\n  \"id\":\"3\",\n  \"applicationId\":1155743,\n  \"portalId\":12345678,\n  \"eventTypeId\":123,\n  \"objectType\":\"CONTACT\",\n  \"objectId\":1,\n  \"extraData\":{\n    \"name\":\"John Doe\",\n    \"weather\":\"Cloudy\"\n  },\n  \"presentationId\":\"9876543\",\n  \"timestamp\":1416853283688\n}"