Smart Pill for Measuring Gut Health in Colon Inflammation and Colon Cancer

The goal of this observational pilot study with invasive measurements is to explore whether an ingestible sensor pill can be of use in diagnosis or monitoring of disease in patients with ulcerative colitis or colorectal cancer. The main questions it aims to answer are: * which changes in bowel environment can the sensor pill measure in ulcerative colitis and colorectal cancer before and after treatment? * how practical, effective and user-friendly is the sensor pill for measuring bowel environment in patients with bowel disease? Participants will: * take one sensor pill before treatment and take one sensor pill three months after (start of) treatment; * monitor sensor pill bowel exit using a small wearable device; * answer a questionnaire on experience with the sensor pill; * receive an extra bowel ultrasound (non-endoscopic) three months after start of treatment (only for participants with ulcerative colitis).